Summary

The Historical Damage Assessment Database is a repository of geospatial damage assessments from past National Disaster events where damage assessments were conducted either using high-resolution imagery or by means of geospatial modeling. The purpose of generating geospatial damage assessments is to provide rapid situational awareness of the number of structures impacted.

Methodology

For visual damage assessments using post-event imagery:

Destroyed structures are classified based on a visual post-event imagery review that the structure was collapsed. Affected structures were classified based on a visual post-event imagery review indicating there were missing roof segments, failure of structural elements, and visible damage. Visual imagery assessments are primarily completed using nadir “looking straight down” imagery so damages to the sides of buildings were not included in the visual assessments. Often, imagery was not acquired during peak flood crests on rivers or surge inundation along the coast and as a result, the visual assessments may focus on resulting wind damages, not flood impacts. There may be damages visible on-the-ground that were not assessed using the imagery.

For modeled damage assessments using depth grids:

Damage categories (Affected, Minor, Major, Destroyed) are derived from flood depths at the structure as characterized by the best-available flood depth grid at the time of the damage assessment.

Data Dictionary

Damage Level:

The damage category assigned to the structure based on modeled or visual assessment.

Affected

Minor

Major

Destroyed

Damage Type:

The type of event that created the damage. Multi-event: more than one type of event created damage.

Access & Use Information

Downloads & Resources

Contact

Disclaimers

Assumptions:

The damage assessment point is where the affected building was located.

It is unknown which points indicate structures that are elevated above ground level. Some of these structures may have a ground floor that lies above the inundation layer and as a result, sustained damage was not able to be captured accurately.

Points were partially modified based on their parcel occupancy type, when available. For example: Parcels with PROP_IND_T = “Vacant” were removed from the analysis and parcels with duplicate APNs were removed. These adjustments might cause extra deletions causing some points over structures to not exist in the dataset.

Methodologies used to generate depth grids for flood and surge events do not account for flooding as a result of storm water backups, irrigation ditch failures, flooding from dam or levee breaks, use of spillways and weirs, or resulting wind damages.

User assumes all risk related to the use of this data. FEMA provides this data “as is” and disclaims any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose, and there are no express or implied guarantees of accuracy of the data. In no event will FEMA or any other Federal Agency be liable to you or to any third party for any direct, indirect, incidental, consequential, special, or exemplary damages or lost profit resulting from any use or misuse of this data.